Anisotropy versus exchange in amorphous heavy-rare-earth based RE4Au alloys

We present the results of bulk magnetization measurements on splat-cooled amorphous alloys of composition RE4Au for temperatures ranging between 1.6 and 300 K and in applied field up to 45 kOe. The magnetic properties for alloys over the whole series are summarized. The problem of valency for Eu and Sm in these amorphous alloys is briefly discussed. A special emphasis is placed on non-equilibrium effects in a-Tb4Au.